1. Field of the Invention
The present invention relates to an ultraviolet electromagnetic radiation transmitter/ reflector device comprising a straight glass tube with an end-to-end bore for retaining a pressurised ionising gas, extending therethrough around an axis and defining a radiation transmitter beam.
2. Description of Related Art
It also relates to apparatuses and a process implementing such a device. The invention finds a particularly important, although non-exclusive, application in the field of photochemical treatment of materials by ultraviolet radiation with transmitter tubes containing an ionising gas at high or medium pressure, for example used in the paper industry, textiles, plastics industry, food industry, automobile industry and in the printing field, in particular for polymerization of inks or varnishes on films, for example formed by rolls of paper or cardboard
By high or medium pressure we mean absolute gas pressures greater than or equal to 2 kg/cm.sup.2,for example 3 kg/cm.sup.2 for a medium pressure and greater than 5 kg/cm.sup.2 for a high pressure, being able for example to go up to 100 kg/cm.sup.2.
The invention is not limited to the types of products to be treated. It can for example be used for drying of plated products, for drying of certain varnishes and adhesives, for drying of wire products extending around an axis, or for sterilization of liquid products.
Devices for production and reflection of ultraviolet radiations are already known comprising a straight transmitter tube and a straight concave reflector having a parabolic cross section or an elliptic cross section.
These devices present drawbacks. They are in fact cumbersome and require a transmitter tube completely separated from the reflector by a distance of several millimetres to enable efficient cooling by air flow between the transmitter tube and reflector.
High temperatures from 600 to 900.degree. are in fact observed on the ultraviolet transmitter, whereas the temperature of the reflector is much lower, for example about 50.degree. C.
The materials used are moreover different, the transmitters being made of glass and the reflectors of reflecting metal, of the aluminium type, i.e. presenting a very different thermal expansion coefficient from that of glass.
The tubes of great length of the devices of the prior art moreover present buckling with time.
In the case more particularly concerned by the invention, i.e. ultraviolet radiation transmission, known transmitters also cause formation of ozone in non-negligible quantity.